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What is the Biosphere ?

The biosphere, (from the Greek bios = life, sphaira, sphere) is the layer of the planet Earth where life exists. This layer ranges from heights of up to ten kilometers above sea level, used by some birds in flight, to ocean depths such as the trench in Puerto Rico, more than 8 kilometers deep. These are the extremes; however, in general, the Earth’s layer containing life is thin: the upper atmosphere has little oxygen and very low temperatures, while ocean depths greater than 1000 m are dark and cold. In fact, it has been said that the biosphere is like the shell in relation to the size of an apple.

The development of the term is attributed to English geologist Eduard Suess (1831-1914) and Russian physicist Vladimir I. Vernadsky (1863-1945). The biosphere is one of the four layers that surround the Earth along with the lithosphere (rock), hydrosphere (water), and atmosphere (air) and is the sum of all ecosystems. The biosphere is unique. So far there has been no existence of life in other parts of the universe. Life on Earth depends on the sun.

The energy, provided as sunlight, is captured by plants, some bacteria and protists, in the wonderful phenomenon of photosynthesis. The captured energy transforms carbon dioxide into organic compounds such as sugars and produces oxygen. The vast majority of animal species, fungi, parasitic plants and many bacteria depend directly or indirectly on photosynthesis. The biosphere is the sum total of all ecosystems. It can also be called the zone of life on Earth, a closed and self-regulating system.

From the broadest biophysiological point of view, the biosphere is the global ecological system that integrates all living beings and their relationships, including their interaction with the elements of the lithosphere, hydrosphere and atmosphere. It is postulated that the biosphere has evolved, starting through a process of biogenesis or biopoesis, at least about 3.5 billion years ago. In a broader sense, biospheres are any closed, self-regulating system containing ecosystems, including artificial ones such as Biosphere 2 and BIOS-3, and potentially those of other planets or moons.

The biosphere is incredibly small, just a thin layer around a medium sized planet. But it is also incredibly large, if you consider all the different living things and the vast expanses of water and land on our planet. As with most things that seem large and wide, it is possible to break down the biosphere and use other words to describe specific environments or habitats.

These smaller areas are called “ecosystems” and are characterized by particular geological or climatic features that are adapted to certain forms of life. Oceans, forests, and mountain ranges may be ecosystems, but even more specific places may be their own ecosystems. Think of a cave, a river or river valley, a coral reef, a city, or the “vent communities” that surround black smokers on the ocean floor.

Altitude, latitude, longitude, climate, soils, and terrain can all contribute to the distinctive characteristics of an ecosystem: the Earth’s geological processes have produced a multitude of diverse environments. The biosphere is incredibly diverse and, even under extreme environmental conditions, is an amazing example of the flexibility and resilience of life.

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